Answer to Question #325768 in General Chemistry for Thel

Question

Calculate the boiling point and freezing point of a 1.7 m ethylene glycol solution.

Answer 1

m(ethylene glycol) = 1.7 m;

T_0,f = 0 C = 273 K;

T_0,b = 100 C = 373 K;

K_f(H₂O) = 1.86 K*kg/mol;

K_b(H₂O) = 0.51 K*kg/mol;

$\Delta$ T_f = K_f * m = 1.86 * 1.7 = 3.16 K;

$\Delta$ T_f = T_0,f - T_f;

T_f = T_0,f - $\Delta$ T_f = 273 - 3.16 = 269.8 K = -3.2 C.

$\Delta$ T_b = K_b * m = 0.51 * 1.7 = 0.87 K;

$\Delta$ T_b = T_b - T_0,b;

T_b = T_0,b + $\Delta$ T_b = 373 + 0.87= 373.9 K = +100.9 C.

Answer: T_f = -3.2 C;

T_b = +100.9 C.